1. Field of the Invention
This invention relates to an apparatus for continuously molding and laying structures such as curb stones, ditches or gutters or water channels made from cement and sand mixtures having a fluidity when they are placed and also having a property of setting with lapse of time or thermoplastic materials such as asphalt or resins or sand or aggregates or earth or combination thereof or fluidized clays or other paving material or materials selected in accordance with the purpose thereof.
2. Description of the Prior Art
U.S. Pat. No. 2,707,422 discloses an apparatus employing a single screw conveyor which has been used only for laying structures such as curb stones on roads having a comparatively small difference in transverse and longitudinal dimensions.
This limited use is due to the fact that although materials having a high fluidity can be easily molded into a mass or lump and also can be continuously laid in a wide range, when laying materials having a low fluidity continuously resultant structures tend to have uneven densities and blowholes or cavities therein which have sometimes caused damages originated therefrom and water leakage problems. On the contrary, when the fluidity of the paving materials to be laid or molded is too high, the paving material will not easily stand by itself, and therefore there occurs a workability problem that permits the molding only of structures which are of low height.
A further important background of the present invention resides in that coupled with the food problem today, in countries with little rainfall, particularly in desert regions, a technique for automatically and continuously forming water channels for irrigation for feeding agricultural products, for tree planting and for making green belts has been desired, and so devices for laying a paving material continuously in a wide range is required to secure a required amount of water flow, and in order to increase the laying or molding rate it is required to keep the fluidity of the paving material being laid as low as possible and eliminate the tendency for the formation of blowholes or cavities in resultant structures due to poor fluidity or insufficient compaction and consolidated settlement thereof.
However, there is at the present time no device which can solve these problems and be put to practical application.